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    <title>ShellCheck: SC1138 – Shells are space sensitive. Use `< <(cmd)`, not `<< (cmd)`.</title>
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    <h1>SC1138 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC1138">See this page on GitHub</a>
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    <h2 id="shells-are-space-sensitive-use--cmd-not--cmd">Shells are space
sensitive. Use <code>&lt; &lt;(cmd)</code>, not
<code>&lt;&lt; (cmd)</code>.</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC1138.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="cf">while</span> <span class="bu">read</span> <span class="at">-r</span> <span class="va">line</span></span>
<span id="cb1-2"><a href="SC1138.html#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">do</span></span>
<span id="cb1-3"><a href="SC1138.html#cb1-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">echo</span> <span class="st">&quot;You said: </span><span class="va">$line</span><span class="st">&quot;</span></span>
<span id="cb1-4"><a href="SC1138.html#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="cf">done</span> <span class="op">&lt;&lt;</span><span class="kw">(</span><span class="ex">cmd</span><span class="kw">)</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC1138.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="cf">while</span> <span class="bu">read</span> <span class="at">-r</span> <span class="va">line</span></span>
<span id="cb2-2"><a href="SC1138.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="cf">do</span></span>
<span id="cb2-3"><a href="SC1138.html#cb2-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">echo</span> <span class="st">&quot;You said: </span><span class="va">$line</span><span class="st">&quot;</span></span>
<span id="cb2-4"><a href="SC1138.html#cb2-4" aria-hidden="true" tabindex="-1"></a><span class="cf">done</span> <span class="op">&lt;</span> <span class="op">&lt;(</span><span class="ex">cmd</span><span class="op">)</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p>When redirecting <code>&lt;</code> from a process substitution
<code>&lt;(cmd)</code>, make sure there is a space between the two
<code>&lt;</code> characters as shown in the example.</p>
<p>With a space <code>cmd1 &lt; &lt;(cmd2)</code>, is correctly
interpreted as "run cmd1, reading stdin from cmd2, without forking for a
pipeline".</p>
<p>Without a space, <code>&lt;&lt;</code> is incorrectly considered a
here document, and <code>(cmd2)</code> is an invalid delimiter
token.</p>
<h3 id="exceptions">Exceptions:</h3>
<p>None</p>
<h3 id="related-resources">Related resources:</h3>
<ul>
<li>Help by adding links to BashFAQ, StackOverflow, man pages, POSIX,
etc!</li>
</ul>
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